European patent publications 0,486,316; 0,496,891; and, 0,500,393 as well as U.S. Pat. No. 5,208,629 disclose such illuminating arrangements for symmetrically inclined illumination with two or four light beams. In each case, displacement possibilities are provided. Thus, European patent publication 0,486,316 discloses shifting the geometry of the quadrupole illumination by displacing light conductors (FIGS. 12 and 13) or lenses (FIG. 17) or lens arrays (FIG. 35) and FIG. 38 shows the arrangement of various lens rasters on a turret with two and four light beams and a conventional simple light beam. This last configuration is also presented in claim 13 of European patent publication 0,496,891. According to claim 12 of this publication, angles and spacing of the quadrupole illumination are adjustable and in claim 14, a switchover electro-optical filter for defining the various types of illumination is presented. European patent publication 0,500,393 includes FIG. 16 which also shows a turret for different types of illumination.
The above-mentioned European patent publications provide that the light of a light source collected by a single collector is subdivided by known means into one, two or four light fluxes in order to obtain the desired number of secondary light sources.
Only European patent publication 0,500,393 provides, as an alternative, the arrangement of two lamps (FIG. 12). The light spots are always circular in shape or quadratic. U.S. Pat. No. 5,208,629 includes FIG. 80 which also presents four secondary light sources each having a shape corresponding to an annular segment but without providing information as to the generation or displacement thereof.
European patent publication 0,297,161 collects the light of a light source with two opposite-lying collectors and conducts the light via mirrors into the pupillary plane. Displacement possibilities and other than conventional illumination are not provided. The arrangement includes a glass rod and a special filter which can be mounted directly on the reticle or on the output of the glass rod.
None of the above publications makes any mention of the possibility of scanning when exposing with the exception of U.S. Pat. No. 5,208,629 wherein claims 16 and 62 disclose a rotating inclined illumination with a rotating light spot.
An arrangement of this kind is also disclosed in the article of S. T. Yang et al entitled "Effect of central obscuration on image formation in projection lithography" published in SPIE, Volume 1264, (1990), pages 477 to 485 and in U.S. Pat. No. 3,770,340 for coherent laser illumination and any desired imaging.
An illuminating arrangement for microlithography described in European patent application 0,266,203 provides for: splitting the light of a light source into several light fluxes, simultaneously scanning the light fluxes and the mutual superpositioning thereof (see the abstract and claim 1 of this publication). This operates to suppress disturbances caused by coherent light (see claim 2). Splitting the light into light fluxes takes place without loss by means of geometric light division (see FIGS. 4a to 4d).